Serum ionic fluoride concentrations are related to renal function and menopause status but not to age in a Japanese general population

There have been no studies in which fasting serum ionic fluoride (SIF) concentrations in a general population were investigated despite the fact that SIF has various activities in humans. A total of 332 healthy subjects (167 men and 165 women aged 40 to 69 years) were selected from residents of 2 towns in Iwate Prefecture, Japan using sex-specific and age-specific stratified random sampling methods. Overnight fasting blood samples were collected from all subjects. Serum levels of creatinine, bone alkaline phosphatase and urinary deoxypyridinoline levels were determined in one laboratory. SIF concentrations were measured using highly sensitive methods. Estimated glomerular filtration rate (eGFR) was calculated using serum creatinine level, age and sex. Mean SIF concentrations were 0.495 μmol/l in men and 0.457 μmol/l in women. SIF concentrations were independently related to eGFR in both sexes and to menopause status in women. SIF concentrations in women were significantly higher in the post-menopausal group than in the pre-menopausal group. SIF concentrations in middle-aged healthy subjects were increased with an age-related degeneration in renal function. SIF concentrations in post-menopausal women arise from the increased fluoride release from bone after menopause. Age is not related to SIF concentrations.